Method of displaying virtual information in a view of a real environment

ABSTRACT

A method of displaying virtual information in a view of a real environment comprising the following steps: providing a system for displaying of virtual information in a view of a real environment, determining a current pose of at least one part of the system relative to at least one part of the real environment and providing accuracy information of the current pose, providing multiple pieces of virtual information, and assigning a respective one of the pieces of virtual information to one of different parameters indicative of different pose accuracy information, and displaying at least one of the pieces of virtual information in the view of the real environment according to the accuracy information of the current pose in relation to the assigned parameter of the at least one of the pieces of virtual information.

This application is entitled to the benefit of, and incorporates byreference essential subject matter disclosed in PCT Application No.PCT/EP2011/052900 filed on Feb. 28, 2011, which claims priority toEuropean Application No. 10155026.7 filed Mar. 1, 2010.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention is directed to a method of displaying virtual informationin a view of a real environment in which a system for displaying ofvirtual information in a view of a real environment is provided and acurrent pose of at least one part of the system relative to at least onepart of the real environment is determined.

2. Background Information

In the prior art, applications are known which augment an image orimages generated by at least one camera with virtual information orobjects using the so called Augmented Reality (AR) technology. In suchapplication, a camera coupled to a processing unit such as amicroprocessor takes a picture of a real environment, wherein the realenvironment is displayed in a view to the user on a display screen andvirtual objects may be displayed in addition to the real environment, sothat the real environment displayed on the display screen is augmentedwith virtual objects of any kind. As a display, a display screen (e.g.of a mobile device, such as a smart phone) or an optical see-throughdisplay device (e.g. a semi-transparent head mounted display) may beused. In such application, in order to augment the image with virtualobjects, there is the need for the microprocessor to determine thecurrent position and orientation (termed in the art as “pose”) of thecamera with respect to at least one object of the real environment inorder for the microprocessor to correctly augment the captured imagewith any virtual objects. In this context, correctly augmenting thecaptured image with any virtual objects means that the virtual objectsare displayed in a manner that the virtual objects fit into the scene ofthe image.

In the past, various publications about Augmented Reality and VirtualReality technologies are available.

The present application is concerned with solving a detailed aspect ofcreating an improved method of displaying virtual, location basedinformation. Particularly, in Augmented Reality many concepts ofdisplaying virtual information in a view of a real environment have beenmade public. In Virtual Reality the concept of “level of detail” isknown. Here, different representations of virtual objects can bedisplayed according to graphic-power of the displaying system ordistance to the object.

The present invention solves a problem which has become eminent onlyrecently, with mobile devices and location based services becomingpossible and widespread. Location based services, especially the onesoverlaying virtual data on top of the view of the real world (e.g. acamera image or through a semi-transparent display or by projectivemeans, projection information on the surrounding environment), oftenrely on different means of localization (optional) and means of gettingthe orientation (optional). In other words, location based servicesusing AR technologies often use different pose determination means. Themeans can use data from sensors, which are moving with the user/device(inside-out-mechanisms) or sensors, which are measuring the users'movement from outside (outside-in-mechanisms).

As a simplification, it is referred to in the following and throughoutthe whole application to a “pose”, which could be the position in 1, 2or 3 degrees of freedom or position and orientation in different degreesof freedom or just orientation. The pose can be relative to anearth-centered coordinate system or any other coordinate system (e.g. ofa large building). The virtual information is directly or indirectlypositioned with respect to the coordinate system.

Many methods have been described in the state of the art to determinethe pose of an information system in respect of a coordinate system.Some of the methods use, for example, GPS, compass, or gravity-sensors,other methods rely on images or distance-measurement-devices, and manyother methods are also known. Often these methods combine differentsensors to estimate the pose, or switch between differentsensor-systems, depending on their availability. Sometimes, also thewhole method is switched from one type of pose determination method toanother type of pose determination method.

Further, different sensors and/or different pose determination methodshave different accuracies in determining the pose. For example, a posedetermination method based on a GPS sensor operates at a lower level ofaccuracy (or higher level of inaccuracy, e.g. operates with a higheruncertainty) as compared to an optical based tracking method fordetermining the pose which operates at a higher level of accuracy (orlower level of inaccuracy, e.g. operates with a lower uncertainty). Incombination with various kinds of real world scenarios, this may resultin problems when displaying virtual information in a view of a realworld.

For example, there may be scenarios in which virtual information is tobe displayed at a rather high level of accuracy in order to fit into thescene, for example when the level of detail of the real world is ratherhigh at the location where the virtual information is to be displayed(e.g., in an area of the real world which is rather close to the user).In such a case, the aspect of pose accuracy is rather important. On theother hand, there may also be scenarios in which the level of detail ofthe real world is rather low at the location where the virtualinformation is to be displayed (e.g., in an area of the real world whichis rather distant to the user) and where the aspect of pose accuracy isless important.

Therefore, it would be beneficial to provide a method of displayingvirtual information in a view of a real environment which takes accountof the above mentioned aspects.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a method ofdisplaying virtual information in a view of a real environmentcomprising the steps of providing a system for displaying of virtualinformation in a view of a real environment, determining a current poseof at least one part of the system relative to at least one part of thereal environment and providing accuracy information of the current pose,providing multiple pieces of virtual information, and assigning arespective one of the pieces of virtual information to one of differentparameters indicative of different pose accuracy information, anddisplaying at least one of the pieces of virtual information in the viewof the real environment according to or depending on the accuracyinformation of the current pose in relation to the assigned parameter ofthe at least one of the pieces of virtual information.

For example, the accuracy information contains information on anaccuracy or inaccuracy of the pose determination. In an embodiment ofthe invention, the accuracy information contains information on anuncertainty. Uncertainty, which is a commonly known term in the art, isusually understood as a parameter which defines a variance of values, inthe present case values associated with pose determination. However, thepresent invention may be used in connection with any kind of informationwhich is indicative of pose accuracy. In this regard, it is clear to theskilled person that accuracy information includes information indicativeof inaccuracy (with the terms “accuracy” and “inaccuracy” often usedinterchangeably in the art).

For instance, according to the invention at least one of the pieces ofvirtual information is displayed in the view of the real environmentdepending on whether the accuracy information of the current pose isbeyond the assigned parameter of the at least one of the pieces ofvirtual information.

According to an embodiment, the accuracy information and/or a change inaccuracy information of the current pose is determined by a trackingsystem's own accuracy mechanism, by a time elapsed since last successfulpose estimation of a pose-estimation mechanism, or by a position or achange in position of the system.

According to another embodiment, the accuracy information is determinedfor each component of the pose (degree of freedom) individually or fororientation and position individually, and the method includes assigninga respective one of the pieces of virtual information to one ofdifferent parameters indicative of different pose accuracy information.

The invention, in principle, may be used with any kind of system whichis capable of providing an AR-based service. For example, the method maybe employed on a mobile device, such as a mobile phone, as a number ofmobile phones today offer various required components for AugmentedReality, such as high resolution cameras and displays, accelerometers,orientation sensor, GPS, wireless connectivity by WLAN and/or radiolinks.

Further aspects, embodiments and advantageous features of the inventionare evident from the following disclosure of embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail in conjunction withthe accompanying drawings which illustrate various embodiments of theinvention.

FIG. 1 shows a schematic illustration of an exemplary AR scenario inwhich an embodiment of the invention may be employed;

FIG. 2 shows a flowchart illustration of a method according to anembodiment of the invention;

FIG. 3 shows a flowchart illustration of a method according to anotherembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a schematic illustration of an exemplary AR scenario inwhich an embodiment of the invention may be employed. Particularly, inan example of a possible scenario in which the invention may be used,FIG. 1 shows a birdview of a tradefair. The user 7 holds a mobile device8 to receive virtual information about the different companies andproducts present at the fair. The mobile device is a possibleimplementation of a system for displaying of virtual information in aview of a real environment. However, the invention is not limitedthereto; rather any kind of AR system may be used. For example, thesystem for displaying of virtual information in a view of a realenvironment may also be a distributed system in which processors,display and/or camera etc. are not contained in a common housing.

Generally, a system for displaying of virtual information in a view of areal environment, which may be used for implementing the presentinvention, incorporates or is coupled with a camera (not shown) forgenerating at least one image of the real world, for example containingreal objects 1, 2, 3, 4 as shown. The camera is provided for capturingimages of a real environment and is coupled to a display screen (e.g.provided on the side of mobile device 8 facing the user 7) for providinga view of the real environment. However, any other image displayingmeans may be used which is suitable for displaying a view to a user,such as a semi-transparent head mounted display or any other type ofmobile or stationary display device. Furthermore, the system includes aprocessing device (not shown), which may be for example amicroprocessor.

In the present implementation, the processing device is connected withor incorporated in the mobile device 8. In a particular non-limitingapplication, the mobile device 8 may be a mobile telephone having anintegrated orientation sensor, camera, touchscreen, and processingdevice. Further, the mobile device 8 may comprise an accelerometer, GPS,wireless connectivity by WLAN and/or radio links. For the purposes ofthe invention, the components may also be distributed and/or used indifferent applications. Further, they may be coupled with each other inwired or wireless fashion. According to another embodiment, the systemor mobile device, respectively, could also be a fixed installationinside a car or any other vehicle.

One or more of the above components may be used for determining acurrent pose of at least one part of the system relative to at least onepart of the real environment. With determining the current pose,accuracy information of the current pose is also provided. for example,when determining the pose by means of GPS an uncertainty of 40(indicative of an uncertainty of 40 meters) is provided, whereas whendeteimining the pose by means of optical tracking an uncertainty of 1(indicative of an uncertainty of 1 meter) is provided. In this case, theuncertainty indicates a variance of possible pose values within a rangeof 40 m or 1 m, respectively.

In the state of the art, the system's accuracy is often also describedby an expected error value and an uncertainty, all these differentdefinitions not changing the direction of the concept of the presentinvention. We just expect the system to react to the accuracy definitionaccording to the way it is modeled.

On the displaying means of the mobile device 8, an image of the realenvironment may be augmented with virtual information, such as POIs(“point of interest” commonly termed as POI) by displaying the virtualinformation superimposed with the real environment in the view inaccordance with the pose of the camera. The pose of the camera may be,for example, the pose with respect to the real objects 1, 2, 3, or 4. Tothis end, the pose may be determined with respect to a coordinate system(not shown), which in turn is associated with the respective object ofthe real world. In the scenario of FIG. 1, there could be two mainbuildings 1 and 2 with different areas, e.g. 5 and 6. On each area therecould be different products 3, 4 shown to the public of the trade fair.According to the present invention, the user 7 could be presented withdifferent virtual visualizations not only according to the pose, butalso to the pose-estimation-method's accuracy (or a combination). Tothis end, the system in the mobile device 8 holds or accesses multiplepieces of virtual information (such as multiple POIs), wherein arespective one of the pieces of virtual information is assigned to atleast one of different parameters indicative of or related to differentpose accuracy information (cf. step 2.0 in FIGS. 2 and 3 retrieving suchparameters). For example, a POI associated with one of the buildings 1,2 is assigned to a parameter which is indicative of a pose accuracyinformation (e.g., uncertainty) of 40 meters. On the other hand, a POIassociated with one of the products 3, 4 is assigned to a parameterwhich is indicative of a pose accuracy information (e.g., uncertainty)of 1 meter.

For example, if the user 7 is outside the buildings 1, 2, he might justget displayed an indication of POIs related to the buildings, becausethe pose of the mobile device is determined using GPS and a compasshaving a rather high uncertainty (rather low accuracy). The informationabout the areas 5, 6 and the products 3, 4 is not shown, because theaccuracy might be around 40 meters.

The user might now move inside building 2, where a more accuratepose-estimation-method could be used, e.g. adding wirelessLAN-localization mechanisms. Now, the uncertainty of the posedetermination might be around 10 meters. The pieces of virtualinformation about the buildings 1, 2 might now disappear and insteadpieces of virtual information (e.g. POIs) about the different areas 5, 6appear. The user 7 can use this information to orient and navigate tothe area of his choice. When reaching area 6, an optical trackingmechanism could be started, which was trained with data of that area, ora QR-code (QR means quick response, which is a commonly known term inthe logistics and in the mobile field) or a marker holdingposition-information could be detected. Now the accuracy changes to 1meter or less. At this point, virtual product information, e.g. as a3D-overlay, could appear and be displayed to the user. In this case thevirtual information about areas 5, 6 could also stay visible.

In order to provide accuracy information of the current pose or todetect when the accuracy changes, different mechanisms may be used. Theaccuracy information can be retrieved from the pose-estimation-methoditself or by the fusion of different accuracies of different individualpose-estimation-methods. For example

1. Time: the system can assume that after a certain time of notreceiving a high-accuracy result from the more accurate tracking system,the overall system accuracy is adapted to the accuracy of the sensorwhich is delivering data. For example, after the scan of a QR-code(“Quick Response”, standard code known in the art) or optical detectionof an object, the system assumes the higher accuracy for a certainamount of time (e.g. 30 seconds). The duration of this time span can beconfigurable, depending on the pose estimation mechanism or the location(e.g. assuming the user spends a certain amount of time at a certainlocation after scanning a QR-code).

2. Current position or position based on prediction of movement: Formany pose determination systems, the covered area in which the systemoperates is known. For example, if a camera, mounted at the ceiling of aroom, is used to determine the user's position, the accuracy changes assoon as the user moves out of that camera's field of view. For a systemwhich e.g. relies on the detection of objects in a camera image of adevice- mounted camera, often the area of possible object detection andtracking is known. If the user moves outside of this area, the overallsystem's accuracy can immediately be reset. Some pose determining meansnot only rely on absolute measurements with respect to a knowncoordinate system, but track the pose in relation to a previous posebased on motion sensors or camera images (e.g. using optical flow, seean advanced use here: “Hybrid Tracking Approach Using Optical Flow AndPose Estimation”, Muriel Pressigoutn, Eric Marchand, and Etienne Mervin,in IEEE Int. Conf. on Image Processing, ICrP'08 (2008).

If the user e.g. scans a QR-code which has a location encoded within thecode, the accuracy degrades drastically as soon as the user moves away.This movement can be detected using a mechanism as described in“Determining the instantaneous axis of translation from optic flowgenerated by arbitrary sensor motion”, J. H. Rieger, D. T. Lawton, inSIGGRAPH Comput. Graph. 18, 1 (January 1984), 24-24. In addition, theaccuracy can the mechanism can of course be treated individually fordifferent components of the pose. For example, the rotation sensors areused to determine the orientation of the system and QR-codes and GPS areused to determine the location of the system.

3. Tracking system's own accuracy mechanisms: As discussed before, forexample, many tracking systems have their specific uncertaintydetermination methods and can deliver uncertainty data dynamically.

Accordingly, in the method of the present invention, at least one of thepieces of virtual information is displayed in the view of the realenvironment according to the accuracy information of the current pose inrelation to the assigned parameter of the at least one of the pieces ofvirtual information. In other words, the method includes the step ofassigning different pieces of virtual information to different valuesrelated to accuracy information, and displaying the pieces ofinformation according to accuracy information of the current pose.

For example, a respective piece of virtual information is displayed, ornot, or displayed in a different appearance or visualization methodetc., if the accuracy information of the current pose is equal to orbeyond a threshold defined by the respective assigned parameter. Forexample, at least one of the multiple pieces of virtual information isnot displayed when the accuracy information of the current pose is equalto or beyond a certain threshold.

In this regard, FIG. 2 shows a flowchart illustration of a methodaccording to an embodiment of the invention. Step 1.0 includes the stepof determining an uncertainty of the current pose (e.g. 10 meters),whereas in step 2.0 POIs around this pose and their uncertaintyparameters (e.g. “min uncertainty”=15 m, “max_uncertainty”=5 m) areretrieved. Part of this process can run in parallel or in sequence (e.g.POIs are not always retrieved freshly). The smaller uncertainty, thebetter is the current tracking. “Max_uncertainty” designates: only showobjects at good tracking. “Min uncertainty” designates: only showobjects at bad tracking. One of these values could be optional.

In step 3.0 it is decided for each one of the POIs whether it is shownor not. In a first optional substep, it is decided whether the distanceto the object of the real environment associated with the POI is lessthan a parameter indicative of a distance to the object(“max_distance”). If yes, and if the uncertainty of the current pose isless than “max uncertainty”, then the respective POI is displayed. Ifnot, and if the uncertainty of the current pose is greater than “minuncertainty”, then the respective POI is not displayed. If, however, theuncertainty of the current pose is equal to or less than “minuncertainty”, then the respective POI is displayed. In this case, theuncertainty of the current pose is in a range between the two parameters“min uncertainty” and “max uncertainty”. Certainly, to avoid too manyswitches in a short amount of time, the values can also be given anadditional value, which expects not only being over and under athreshold, but also a certain change in a certain amount of time.

Accordingly, a first number of the multiple pieces of virtualinformation (POIs) are displayed when the accuracy information of thecurrent pose is within a first range, and a second number of themultiple pieces of virtual information (POIs) are displayed when theaccuracy information of the current pose is within a second rangedifferent from the first range. For example, some POIs are not shownwhen the accuracy has reached a certain threshold (e.g. show some POIs,when the accuracy is high, and show other POIs, when the accuracy islow)

An embodiment of the invention includes the following steps: clusteringa number of the pieces of virtual information, creating a superordinatepiece of virtual information from the clustered number of pieces ofvirtual information, and assigning the superordinate piece of virtualinformation to a parameter indicative of pose accuracy information whichis different from the parameters assigned to the clustered number ofpieces of virtual information. In this way, a single virtual informationcan be generated which is displayed when displaying of the number ofpieces of virtual information makes no sense (e.g. automaticallygenerating different levels of accuracy from information by clusteringlocal, detailed information and creating a single piece of information,accordingly. E.g., clustering virtual information related to products 3and 4 of FIG. 1 and creating a superordinate virtual informationtherefrom which is associated to area 6 automatically and displayed whenthe current pose uncertainty is higher than the uncertainty parameter ofthe virtual information related to the products 3, 4.).

An embodiment of the invention includes the following steps: assigning arespective one of the pieces of virtual information to a respectivesecond parameter indicative of a distance, determining a currentdistance of at least one part of the system to at least one part of thereal environment, and displaying at least one of the pieces of virtualinformation in the view of the real environment according to ordepending on whether the current distance is beyond the assigned secondparameter of the at least one of the pieces of virtual information.Accordingly, information may be displayed according to a furtherPOI-parameter (second parameter) which indicates the maximum distancewhere the information makes sense to be displayed. If the currentdistance is beyond that POI-parameter, then the respective POI will notbe displayed.

According to a further embodiment of the invention, providing accuracyinformation of the current pose includes differentiating the accuracyinformation of the current pose depending on whether an optical or anon-optical pose determination method is used.

An embodiment of the invention includes the following steps: displayingat least one of the pieces of virtual information in the view of thereal environment according to a combination of the accuracy informationof the current pose and a distance of at least one part of the system tothe position of the at least one of the pieces of virtual information inrelation to the real environment (e.g. not displaying near virtualinformation at low accuracy, but displaying far virtual information atlow accuracy, since the higher the distance the lower is the impact oflocation-inaccuracy).

An embodiment of the invention includes displaying at least one of thepieces of virtual information in the view of the real environment usingdifferent appearances or visualization methods depending on the accuracyinformation of the current pose (e.g. a floating image in case of lowaccuracy and a 3D-object in case of high accuracy).

In this regard, FIG. 3 shows a flowchart illustration of a methodaccording to another embodiment of the invention. Basically, the processas shown in FIG. 3 may be implemented independently or in combinationwith the process as shown in FIG. 2. In the present embodiment of FIG.3, steps 1.0 and 2.0 are basically the same as in FIG. 2. In step 2.0,additional parameters “max_uncertainty_level 1” and“max_uncertainty_level2” may be defined which are used in step 3.0 asshown. In step 3.0, the display method of each piece of virtualinformation (e.g., POI) is determined. The substeps are analogous orcomparable to that of FIG. 2 with the results in steps 3.1 A to 3.1 C asindicated in FIG. 3.

Particularly, in step 3.0 it is decided how POIs are displayed. If theuncertainty of the current pose is less than “max uncertainty level1”,then the respective POI is displayed as 3D-model. If not, and if theuncertainty of the current pose is less than “max_uncertainty_level2”,then the respective POI is displayed as image-overlay. Otherwise, therespective POI is not displayed. Basically, it is possible to define anynumber of levels comparable to “max uncertainty level1” and“max_uncertainty_level2”

An embodiment of the invention includes displaying at least one of thepieces of virtual information in the view of the real environmentperspectively correctly overlayed on the real environment in case of ahigher accuracy of the current pose and non-correctly overlayed in caseof a lower accuracy of the current pose.

An embodiment of the invention includes providing an information systemwhich is capable of providing, in a first mode, an augmented realityview and, in a second mode, a map-view, wherein the step of displayingat least one of the pieces of virtual information according to theaccuracy information of the current pose is performed in the augmentedreality view, but not in the map view. As such, the accuracy informationper piece of virtual information is considered in the augmented realityview, but not in the map view.

A further embodiment of the invention includes determining thevisibility of drawing style of a piece of virtual information not onlyaccording to the accuracy information of the current pose, but alsoaccording to a distance and/or information about occluding objects inthe real environment and /or a current speed of a display of the systemwith respect to a coordinate system which is fixed with respect to thereal environment.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the claims.Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed, but that the invention will includeall embodiments falling within the scope of the appended claims.

1. A method of displaying virtual information in a view of a realenvironment comprising the following steps: providing a system fordisplaying of virtual information in a view of a real environment;determining a current pose of at least one part of the system relativeto at least one part of the real environment and providing accuracyinformation of the current pose; providing multiple pieces of virtualinformation, and assigning a respective one of the pieces of virtualinformation to one of different parameters indicative of different poseaccuracy information; and displaying at least one of the pieces ofvirtual information in the view of the real environment according to theaccuracy information of the current pose in relation to the as-signedparameter of the at least one of the pieces of virtual information. 2.The method of claim 1, wherein the accuracy information containsinformation on an uncertainty.
 3. The method of claim 1, wherein atleast one of the multiple pieces of virtual information is not displayedwhen the accuracy information of the current pose is equal to or beyonda certain threshold.
 4. The method of claim 3, wherein a first number ofthe multiple pieces of virtual information are displayed when theaccuracy information of the current pose is within a first range, and asecond number of the multiple pieces of virtual information aredisplayed when the accuracy information of the current pose is within asecond range different from the first range.
 5. The method of claim 1,further comprising the steps of: clustering a number of the pieces ofvirtual information; creating a superordinate piece of virtualinformation from the clustered number of pieces of virtual information;and assigning the superordinate piece of virtual information to aparameter indicative of pose accuracy information which is differentfrom the parameters assigned to the clustered number of pieces ofvirtual information.
 6. The method of claim 1, further comprising thesteps of: assigning a respective one of the pieces of virtualinformation to a respective second parameter indicative of a distance;determining a current distance of at least one part of the system to atleast one part of the real environment; and displaying at least one ofthe pieces of virtual information in the view of the real environmentaccording to the current distance in relation to the assigned secondparameter of the at least one of the pieces of virtual information. 7.The method of claim 1, wherein providing accuracy information of thecurrent pos includes differentiating the accuracy information of thecurrent pose depending on whether an optical or a non-optical posedetermination method is used.
 8. The method of claim 1, furthercomprising the step of: displaying at least one of the pieces of virtualinformation in the view of the real environment according to acombination of the accuracy information of the current pose and adistance of at least one part of the system to the position of the atleast one of the pieces of virtual information in relation to the realenvironment.
 9. The method of claim 1, further comprising the step of:displaying at least one of the pieces of virtual information in the viewof the real environment using different appearances or visualizationmethods depending on the accuracy information of the current pose. 10.The method of claim 1, further comprising the step of: displaying atleast one of the pieces of virtual information in the view of the realenvironment perspectively correctly overlayed on the real environment incase of a higher accuracy of the current pose and non-correctlyoverlayed in case of a lower accuracy of the cur-rent pose.
 11. Themethod of claim 1, further comprising the step of: providing aninformation system which is capable of providing, in a first mode, anaugmented reality view and, in a second mode, a map-view, wherein thestep of displaying at least one of the pieces of virtual informationaccording to the accuracy information of the current pose is performedin the augmented reality view, but not in the map view.
 12. The methodof claim 1, further comprising the step of: determining the visibilityof drawing style of a piece of virtual information not only according tothe accuracy information of the current pose, but also according to adistance and / or information about occluding objects in the realenvironment and/or a current speed of a display of the system withrespect to a coordinate system which is fixed with respect to the realenvironment.
 13. The method of claim 1, wherein the accuracy informationand/or a change in accuracy information of the current pose isdetermined by a tracking system's own accuracy mechanism, by a timeelapsed since last successful pose estimation of a pose-estimationmechanism, or by a position or a change in position of the system. 14.The method of claim 1, wherein the accuracy information is determinedfor each component of the pose individually or for orientation andposition individually, and assigning a respective one of the pieces ofvirtual information to one of different parameters indicative ofdifferent pose accuracy information.